Engineered textile yarn

ABSTRACT

The present invention relates to integral protective overalls for operations on uncovered high-voltage cables, comprising a first electrically conductive layer whose surface area is substantially equal to the surface area of the overalls and that is obtained from a polymer fibre covered with silver. The overalls of the present invention can also include a second layer connected to the first layer in a stable manner.

The present invention relates to an anti-electric-shock garment according to the preamble of claim 1.

Such a garment is known, for example, as a protective garment for technicians who carry out maintenance operations on live high-voltage wires.

When the high-voltage wires are damaged, it is necessary to repair them in order to prevent them from breaking and causing considerable damage, both to the structures and in terms of a break in the supply of the service.

Clearly, the activity of the technicians is aimed at minimising the risks of discharge (or short circuit) between two different phases of the high voltage, which may reach potential differences on the order of 800 kV AC or 600 kV DC.

Clearly it is desirable to have garments capable of providing protection even if a short circuit is created in spite of the precautions taken.

The garments known hitherto in the prior art are made of steel wire braided with cotton thread; however, they have a number of disadvantages: their electrical resistance, measured between any two points, is relatively high; they must be ‘activated’ before each use by a strong electrical discharge in order to restore their original electrical conductivity; finally, because of its rigidity, the steel wire gives rise to rigid and uncomfortable garments that hamper the movements of the operators, with a consequent further decrease in the operative safety margins.

For this reason, a European Standard, IEC 60895: 2002, was approved recently that defines some parameters that must be measured to characterise garments that are suitable for these purposes, among them:

-   resistance to abrasion and to wear; -   flame-retardant properties; -   low electrical resistance; -   capacity to conduct capacitive currents; -   protection and shielding capacity; -   resistance to cleaning cycles; -   protection against sparks.

Besides these parameters, the Standard defines other parameters specific to garments that protect only some parts of the body: for gloves, boots, socks, and footwear, the measuring method of the maximum resistance measure is defined; for garments that shield the head and the face, the efficiency of protection of the face is also defined.

The necessity for safety garments that are ever more effective and simple to use in this field is continually underlined by the too frequent accidents recorded almost daily all over the world.

The present invention is therefore aimed at satisfying specifically the needs of operators who carry out maintenance work on high-voltage electrical lines.

In view of the prior art described, the object of the present invention is to obtain a protective garment that allows technicians to work with greater safety during operations on live high-voltage wires, with the efficiency of the garment being measured according to the parameters defined by the Standard indicated above.

According to the present invention, this object is achieved by means of a garment in accordance with claim 1.

The features and the advantages of the present invention will become evident from the following detailed description of a practical form of embodiment given as a non-limiting example with reference to the attached drawings in which:

FIG. 1 shows a view of a preferred embodiment of a garment according to the present invention;

FIG. 2 shows a schematic view of one of the components o

According to the invention, the garment 1 comprises at least one first electrically conductive layer whose extent substantially coincides with the extent of the garment 1 itself. This first layer may include a conductive yarn 2; advantageously, it is composed exclusively of this conductive yarn 2.

This means that the garment 1 is composed of a substantially complete electrically conductive layer on which can be superimposed other different layers, even partial layers, however without there being substantial portions of the garment 1 where this first electrically conductive layer is absent.

If the first layer is a textile product, for instance, the spaces between two adjacent threads need not be considered as areas of substantial discontinuity for the purposes of the present invention.

The conductive yarn 2 visible in FIG. 2 may contain silver; for example it may have a core 3 covered by a layer 4 of silver, for example by means of spraying.

Advantageously the core 3 is a polymer, for example composed of polyamide filaments. In a preferred embodiment, about 80% of the mass of the yarn 2 is silver.

Using the silver as a conductor, advantageously a garment 1 is obtained that is also endowed with antibacterial and bacteriostatic properties.

The conductive yarn 2 can also be one of those described in the international patent application with the title ‘CONDUCTIVE TEXTILE YARN’, filed on 22 Mar. 2007 in the name of the holder of the present application, for example produced by braiding a polyamide filament covered with silver with an aramide thread, or twisting together polyamide fibres covered with silver and aramide fibres.

Preferably the garment 1 is overalls 5 capable of covering the legs, th the operator. In a preferred embodiment, the garment 1 also comprises a hood 6 and/or a visor 7 and/or one or more loop fastenings 8, to cover also the nape of the neck and part of the face of the operator. Advantageously, all these elements are integrated together.

Furthermore, the garment 1 can cover also the feet and/or the hands, for example by means of boots 9 and/or gloves 10 integrated with the overalls 5 or that can be connected thereto.

In this way it is possible to obtain a continuous covering that produces an almost perfect Faraday cage, allowing the garment 1 to satisfy the requirements relating to electrical properties, established by the Standard cited above.

The conductive textile product is advantageously a fabric, preferably a knit, for example made with a loom 30 inches in diameter, of fineness 28, with ‘interlock’ weave, and with a weight of 200 g/sqm (±5%) after removal from the machine.

Clearly, these values refer to the best embodiment, but suitable products can also be obtained with circular or straight knitting machines or with traditional looms for weaving (warp and weft). Similarly, the diameter, the fineness, and the weight after removal from the machine can vary.

According to an advantageous embodiment, the garment 1 comprises, connected in a stable manner to the first layer, at least one second layer that provides the garment 1 with the properties of mechanical and/or chemical and/or flame resistance, as prescribed by the Standard cited initially. Preferably a single layer provides all these properties.

Advantageously, both the layers are produced in the form of a knit; they can be connected to one another in a stable manner.

The second layer can be composed of a second textile product, for example a fibre endowed with anti-flame or flame-retardant properties, such as for example a fibre selected from the group comprising aramide fibres, meta-aramide fibres, treated natura fibres, flame-retardant viscose, flame-retardant cotton, Lenzing FR®.

The two layers can be coupled together in a stable manner by means of quilting or, more advantageously, by means of coupling (chemical or mechanical) over the entire extent of their contact surfaces.

The coupling can be achieved both chemically, that is by placing a resin between the two yarns, for example a flameproof and preferably polyurethane resin, that acts as an adhesive without compromising the elastic properties of the knits, and mechanically, that is by weaving at least one conductive thread for the first layer and at least one thread for the second layer at the same time, but separated, on the same weaving machine.

In order to contribute to keeping the electrical resistance of the garment 1 low, at least some of the internal stitches between two fabric parts (for example undersleeve, oversleeve), advantageously all the stitches, are double and felled and/or overlocked.

The garment 1 can include, on the breast, a metal frame covered by a flap 11. The flap 11 can be closed on the breast of the garment 1 by means of a number of press studs 12, for example alternating with strips of hook-and-loop fasteners 13, arranged on the free edge of the flap 11 itself.

Corresponding to the zones subjected to higher mechanical forces, the garment 1 comprises reinforcing padding, advantageously made of nonwoven material. For example, such reinforcements are present in the vicinity of the closure studs 12 or in the vicinity of the hook-and-loop fasteners 13.

The hood 6 of garment 1 can include one or more loop fastenings 8 to protect the neck and the face respectively; to protect the eyes, it has proved to be sufficient to produce a substantially rigid visor 7, for example reinforced with nonwoven material. To ensure a greater shielding of the eyes and the nose, visor 7 is sewn to hood 6 by means of a slanting stitch, preferably slanting in the upwards direction, in such a way the and pushed to rotate downwards.

In this manner the use of a shield for the eyes becomes superfluous. The garment 1 according to the present invention thus does not need to include a transparent shield to protect the eyes, which allows an even greater comfort in use.

As it can be seen, with the present invention an extremely conductive protective garment 1 has been produced, a garment that is greatly more elastic than the overalls currently available commercially, thus obtaining a garment 1 capable of increasing the safety of the operators both by means of the protection against the external agents in the proper sense (electricity, aggressive chemical and/or mechanical agents, flames), and because it is much more comfortable than the garments known hitherto.

This garment 1 is the only one up to now capable of satisfying the Standard IEC 60895:2002.

In particular, the garment 1 according to the present invention, after being subjected to various tests laid down by this Standard, has shown the following results:

-   -   a maximum resistance of less than 10 ohm, more precisely less         than 3 ohm, even more precisely less than 1 ohm, for the         electrical resistance test;     -   a measured resistance of less than 5 ohm, more precisely less         than 2 ohm, even more precisely less than 0.5 ohm, for the test         of electrical resistance on samples of fabric;     -   a shielding efficiency greater than 40 dB, more precisely         greater than 60 dB, even more precisely greater than 70 dB,         better if greater than 75 dB, for example greater than 79 dB on         new samples and greater than 78.8 dB on washed samples.

Obviously one skilled in the art, for the purpose of satisfying contingent and specific needs, will be able to introduce numerous modifications and variants to the configurations described above, but all contained within the scope of protection of the invention as defined by the following claims. 

1-13. (canceled)
 14. A protective anti electric-shock garment for operations on uncovered high-voltage cables, comprising a first electrically conductive layer, wherein the surface area of the said first layer is substantially equal to the surface area of the said garment.
 15. A protective anti electric-shock garment according to claim 14, wherein the said first conductive layer is obtained from a conductive yarn covered in silver.
 16. A protective anti electric-shock garment according to claim 14, comprising at least one second yarn having flame-retardant properties, obtained from a polyaramide fibre.
 17. A protective anti electric-shock garment according to claim 16, wherein the said first and second layers are coupled together in a stable manner over the entire extent of the surfaces of mutual contact of the said first and second layer.
 18. A protective anti electric-shock garment according to according to claim 14, wherein the shielding efficiency, measured according to Standard IEC 60895:2002, is greater than 20 dB, preferably greater than 70 dB.
 19. A protective anti electric-shock garment according to claim 14, comprising trousers, a covering for the abdomen, and sleeves, produced without a break in continuity between them.
 20. A protective anti electric-shock garment according to claim 14, comprising boots and/or gloves, each capable of being joined to the said garment by means of at least two press studs having a diameter of not less than 10 mm.
 21. A protective anti electric-shock garment according to claim 20, refolded in correspondence with these press studs, in such a way that the said conductive layer is present with continuity also to the inside of the said garment, in such a way as to form an electrical contact both with the external portion and with the internal portion of the said press studs.
 22. A protective anti electric-shock garment according to claim 14 that comprises double or overlocked stitches.
 23. A protective anti electric-shock garment according to according to claim 14 that comprises a hood capable of being arranged around the head of the user, the said hood being such as to leave only the face uncovered.
 24. A protective garment according to claim 23 wherein the said hood is equipped with one or more loop fastenings capable of being arranged around the face in such a way as to leave uncovered only the eyes of the user.
 25. A protective anti electric-shock garment according to claim 23 wherein the said hood comprises a rigid visor.
 26. A protective anti electric-shock garment according to claim 25 wherein the said rigid visor is sewn to the said hood by means of a stitch slanting in the upwards direction, in such a way as to impart to the said visor a torque that tends to rotate it towards the face of the user. 